title: Bortezomib interacts synergistically with belinostat in human acute myeloid leukaemia and acute lymphoblastic leukaemia cells in association with perturbations in NF-κB and Bim.
abstract: Interactions between the histone deacetylase inhibitor belinostat and the proteasome inhibitor bortezomib were investigated in acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL) cells. Co-administration of sub-micromolar concentrations of belinostat with low nanomolar concentrations of bortezomib sharply increased apoptosis in both AML and ALL cell lines and primary blasts. Synergistic interactions were associated with interruption of both canonical and non-canonical nuclear factor (NF)-κB signalling pathways, e.g. accumulation of the phosphorylated (S32/S36) form of IκBα, diminished belinostat-mediated RelA/p65 hyperacetylation (K310), and reduced processing of p100 into p52. These events were accompanied by down-regulation of NF-κB-dependent pro-survival proteins (e.g. XIAP, Bcl-xL). Moreover, belinostat/bortezomib co-exposure induced up-regulation of the BH3-only pro-death protein Bim. Significantly, shRNA knock-down of Bim substantially reduced the lethality of belinostat/bortezomib regimens. Administration of belinostat ± bortezomib also induced hyperacetylation (K40) of α-tubulin, indicating histone deacetylase inhibitor 6 inhibition. Finally, in contrast to the pronounced lethality of belinostat/bortezomib toward primary leukaemia blasts, equivalent treatment was relatively non-toxic to normal CD34(+)  cells. Together, these findings indicate that belinostat and bortezomib interact synergistically in both cultured and primary AML and ALL cells, and raise the possibilities that up-regulation of Bim and interference with NF-κB pathways contribute to this phenomenon. They also suggest that combined belinostat/bortezomib regimens warrant further attention in acute leukaemias.
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Virginia Commonwealth University and the Massey Cancer Center, VCU Health Sciences Center, 401 College Street, Richmond, VA 23298, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Dai
authors.forename: Shuang
authors.initials: S
authors.lastname: Chen
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Xin-Yan
authors.initials: XY
authors.lastname: Pei
authors.forename: Lora B
authors.initials: LB
authors.lastname: Kramer
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
authors.forename: Steven
authors.initials: S
authors.lastname: Grant
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D000072224:Bcl-2-Like Protein 11; D001897:Boronic Acids / Q000494:pharmacology* / Q000627:therapeutic use; D000069286:Bortezomib; D004357:Drug Synergism; D005260:Female; D018922:HL-60 Cells; D000073864:Histone Deacetylase 6; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology* / Q000627:therapeutic use; D051550:I-kappa B Kinase / Q000378:metabolism; D019169:Jurkat Cells; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011719:Pyrazines / Q000494:pharmacology* / Q000627:therapeutic use; D015398:Signal Transduction / Q000187:drug effects; D013449:Sulfonamides; D051996:Transcription Factor RelA / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism; D020298:U937 Cells; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C494811:BCL2L1 protein, human; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; D001897:Boronic Acids; D006877:Hydroxamic Acids; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D011719:Pyrazines; C498143:RELA protein, human; D013449:Sulfonamides; D051996:Transcription Factor RelA; D014404:Tubulin; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D051020:bcl-X Protein; D000069286:Bortezomib; D051550:I-kappa B Kinase; C433811:HDAC6 protein, human; D000073864:Histone Deacetylase 6; D006655:Histone Deacetylases; C487081:belinostat